Coiled stent with locking ends

ABSTRACT

An intravascular stent comprising a cylindrical body capable of expansion having end assemblies capable of locking in an expanded state. The end assemblies may have a series of tabs and apertures that interlock and rotate as the stent ends expand to an open position to support a section of vasculature or other body lumen. The stent is bio-compatible, may be bio-erodible, and capable of localized drug delivery.

This is a division of application Ser. No. 08/209,827, filed Mar. 11,1994, now U.S. Pat. No. 5,556,413.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to expandable endoprosthesisdevices, in particular expandable intraluminal vascular grafts,generally called stents, adapted to be implanted into a body lumen, suchas a coronary artery, to maintain the patency of the lumen. Thesedevices are frequently used in the treatment of atherosclerotic stenosisin blood vessels, especially after percutaneous transluminal coronaryangioplasty (PTCA) procedures, with the intent to help reduce thelikelihood of restenosis of a blood vessel. Stents are also used tosupport a body lumen where a flap or dissection has occurred or ingeneral where the lumen is weak. The present invention also relates toan expandable intraluminal vascular graft that can be used in any bodylumen.

2. Description of Related Art

In typical percutaneous transluminal coronary angioplasty (PTCA)procedures, a guiding catheter having a preformed distal tip ispercutaneously introduced into the cardiovascular system of a patientthrough the brachial or femoral arteries and is advanced therein untilthe distal tip thereof is in the ostium of the desired coronary artery.A guidewire and a dilatation catheter having an inflatable balloon onthe distal end thereof are introduced through the guiding catheter withthe guidewire slidably disposed within an inner lumen of the dilatationcatheter. The guidewire is first advanced out of the distal end of theguiding catheter and is maneuvered into the patient's coronaryvasculature containing the lesion to be dilated, and is then advancedbeyond the lesion. Thereafter, the dilatation catheter is advanced overthe guidewire until the dilatation balloon is located across the lesion.Once in position across the lesion, the balloon of the dilatationcatheter is filled with radiopaque liquid at relatively high pressures(e.g., greater than about 4 atmospheres) and is inflated to apredetermined size (preferably the same as the inner diameter of theartery at that location) to radially compress the atherosclerotic plaqueof the lesion against the inside of the artery wall to thereby dilatethe lumen of the artery. The balloon is then deflated so that thedilatation catheter can be removed and blood flow resumed through thedilated artery.

By way of example, further details of angioplasty and the devices usedin such procedures can be found in U.S. Pat. No. 4,323,071(Simpson-Robert), U.S. Pat No. 4,332,254 (Lundquist), U.S. Pat. No.4,439,185 (Lundquist), U.S. Pat. No. 4,168,224 (Enzmann, et al.), U.S.Pat. No. 4,516,972 (Samson), U.S. Pat. No. 4,582,181 (Samson), U.S. Pat.No. 4,538,622 (Samson, et al.), U.S. Pat. No. 4,597,755 (Samson), U.S.Pat. No. 4,616,652 (Simpson), U.S. Pat. No. 4,748,982 (Horzewski, etal.), U.S. Pat. No. 4,771,778 (Mar), and U.S. Pat. No. 4,793,350 (Mar,et al.), which are hereby incorporated herein in their entirety.

A common problem that sometimes occurs after an angioplasty procedure isthe appearance of restenosis at or near the site of the originalstenosis in the blood vessel which requires a secondary angioplastyprocedure or a bypass surgery. Another occurrence which reduces thesuccess of an angioplasty procedure is that frequently the stenoticplaque or intima of the blood vessel or both are dissected during theangioplasty procedure by the inflation of the balloon. Upon thedeflation of the balloon, a section of the dissected lining (commonlytermed a "flap") will collapse into the bloodstream, thereby closing orsignificantly reducing the blood flow through the vessel. In theseinstances, surgery is sometimes required to avoid a further blockage ofthe artery.

Conceivably, the dilatation catheter could be replaced with a perfusiontype dilatation catheter such as described in U.S. Pat. No. 4,790,315(Mueller, Jr. et al.) in order to hold the blood vessel open forextended periods. However, perfusion type dilatation catheters haverelatively large profiles which can make advancement thereof through theblockage difficult. Additionally, the inflated balloon of theseperfusion catheters can block off a branch artery, thus creatingischemic conditions in the side branch distal to the blockage.

In recent years, various devices and methods (other than bypass surgery)for prevention of restenosis and repairing damaged blood vessels havebecome known which typically use an expandable cage or region (commonlytermed "stent") on the distal end of the catheter designed to hold adetached lining against an arterial wall for extended periods tofacilitate the reattachment thereof. Some stents are designed forpermanent implantation inside the blood vessel and others are designedfor temporary use inside the vessel. By way of example, several stentdevices and methods can be found in U.S. Pat. No. 4,998,539 (Delsanti),U.S. Pat. No. 5,002,560 (Machold, et al.), U.S. Pat. No. 5,034,001(Garrison, et al.), U.S. Pat. No. 5,133,732 (Wiktor), and U.S. Pat. No.5,180,368 (Garrison).

Typically, the expandable region of these stents is formed by a braidedwire attached to the distal end of the catheter body. Such braideddesigns are often difficult and expensive to manufacture, and can createreliability concerns due to the existence of high stress points locatedat the connection of the braided wire region with the catheter body andat the connections between the intermingled wire strands.

Alternatively, the expandable stent can be formed by a helical metal orplastic spring that is mechanically restrained in a contracted stateduring delivery to a predetermined position within a vessel. Afterplacement, the mechanical restraint is released, allowing the helicalspring stent to self-expand rapidly against the inner walls of thevessel. Examples of such stents are disclosed in U.S. Pat. No. 4,768,507(Fischell, et al.), U.S. Pat. No. 4,990,155 (Wilkoff), and U.S. Pat. No.4,553,545 (Maass, et al.).

In expandable stents that are delivered with expandable catheters, suchas balloon catheters, the stents are positioned over the balloon portionof the catheter and expanded from a reduced diameter to an enlargeddiameter, greater than or equal to the diameter of the artery wall, byinflating the balloon. Stents of this type can be expanded to anenlarged diameter by deforming the stent, by engagement of the stentwalls with respect to one another, and by one-way engagement of thestent walls together with endothelial growth into the stent. Examples ofsuch expandable catheters and stents are disclosed in U.S. Patent No.5,102,417 (Palmaz), U.S. Patent No. 5,123,917 (Lee), and U.S. Patent No.5,133,732 (Wiktor) which are hereby incorporated herein in theirentirety.

The disadvantage of many of the current expandable stents is that onceexpanded, they cannot be easily contracted and moved if they are in thewrong position within the lumen. Another problem occurs where the lengthof the stent shortens when expanded, and the stent is no longer largeenough to cover the entire site of repair. In both cases it would beadvantageous to be able to contract the stent, withdraw it from thevessel and replace it if necessary, or reposition it before finalimplantation.

What has been needed, and heretofore unavailable is an intravascularstent that can be placed at the site of a damaged body lumen requiringrepair, evaluated, and repositioned if necessary before being lockedinto place. The present invention fulfills this need.

SUMMARY OF THE INVENTION

The present invention is directed to a stent, adapted to be insertedwithin a body lumen, and designed to expand and lock in an enlargeddiameter form.

The stent of the present invention is designed so that the centralportion of the stent body can be reversibly expanded at a selected sitewithin a vessel lumen. Stent deployment can be accomplished by means ofa two-stage process which allows the physician to abort the procedure ifdesired or if a complication develops. In the first stage, the body ofthe stent is expanded and then evaluated for such criteria as locationrelative to the stenosis and size relative to the vessel in which itresides. At this stage expansion is reversible and the decision toimplant the stent can be aborted. The second stage expands and locks theends of the stent in place so that the stent remains permanentlyimplanted.

During intravascular surgery, the physician can often only estimate theplacement and sizing of the stent when treating a particular lesion.With the present invention, the means for locking the stent into placecan be radiopaque. This allows the physician to readily determine theposition of the stent relative to the lesion during deployment. Theradiopaque ends of the stent allow the stent to be traced withoutblocking visualization of the lesion, allowing the physician todetermine whether the stent is correctly sized to cover the entirelesion. When the physician is satisfied with the stent placement, theends of the stent are designed to lock the stent in its expandedconfiguration.

The stent body may be any geometric design that expands in the centerwhen the ends are either twisted or brought closer together. The firstand second stages of stent expansion may be accomplished by a number ofmethods. The stent of the present invention comprises a variety ofembodiments. In some embodiments of the stent, the stent is locked in anexpanded state by means of a locking ring attached to each end of thestent.

In another embodiment of the stent the locking device comprises aplurality of slots and tabs with teeth such that the slots receive thetabs.

In another embodiment of the stent, the locking device is a ring madefrom a metal or other suitable material that is capable of undergoingplastic deformation. A material undergoes plastic deformation when thematerial is subjected to a force greater than its elastic limit, wherebythe material stretches irreversibly to an enlarged form. In thisembodiment, the locking ring is attached to the individual members ofthe stent. When the stent is properly positioned at the site of repairin the vessel, the locking end is irreversibly expanded to a largerdiameter through plastic deformation of the locking device.

In another embodiment of the stent, the stent and locking device are cutfrom a flat sheet of a suitable material as a single unit. The lockingends are suitably formed to allow them to irreversibly expand throughplastic deformation.

The stent of the present invention may be of a variety of materials,including bio-compatible and bio-resorbable (bio-erodible) polymers,thermal shaped memory polymers or metals, bio-compatible metals,stainless steel, or super elastic materials such as nickel-titaniumalloys. A material constituting the stent can be a thin flexible polymermaterial, such as a polyimide, coated with a thin strengthening materialcomprising a pyrolytic carbon.

The stent may be deployed in a body lumen through a variety of devices,including but not limited to balloon catheters and specialized stentdelivery catheters. These and other advantages of the invention willbecome more apparent from the following detailed description thereofwhen taken in conjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view depicting one embodiment of the presentinvention.

FIG. 2 is a perspective view of the stent of FIG. 1 depicting the stentbody in an expanded state, and the ends in their original contractedstate.

FIG. 3 is a perspective view of the stent of FIGS. 1 and 2 depicting thestent in a fully expanded form with the ends locked in place.

FIG. 4A is a perspective view depicting the locking ring mechanism ofone embodiment of the invention in a contracted state.

FIG. 4B is a perspective view of the locking ring depicted in a lockedstate.

FIG. 5A is a plan view of the locking ring depicted in an unrolledstate.

FIG. 5B is a cross-sectional view taken along line 5--5 depicting thestent in a rolled and reduced diameter form with the free end of thelocking ring shown tucked inside of the stent.

FIG. 5C is a cross-sectional view taken along line 6--6 depicting thestent in an unrolled and expanded diameter form with the free end of thelocking ring shown tucked inside of the stent.

FIG. 6A is a cross-sectional view taken along line 5--5 depicting analternative embodiment of the stent in a rolled and reduced diameterform with the free end of the locking ring shown overlapping theexterior of the stent.

FIG. 6B is a cross-sectional view taken along line 6--6 depicting analternative embodiment of the stent in an unrolled and expanded diameterform with the free end of the locking ring shown overlapping theexterior of the stent.

FIG. 7A is a plan view depicting one method of attaching the lockingring of the present invention to the body of the stent.

FIG. 7B is a plan view depicting another method of attaching the lockingring of the present invention.

FIG. 7C is a partial cross-sectional view taken along line 7C--7Cdepicting a portion of the locking ring of the present invention whereit is attached to the body of the stent.

FIG. 7D is a partial cross-sectional view taken along line 7D--7Ddepicting a portion of the locking ring where it engages the body of thestent.

FIG. 8 depicts an embodiment of the present invention having individualhelical shaped members comprising the body of the stent, and using asystem of tabs and slots at each end of the member to form the lockingdevice.

FIG. 9A is a plan view depicting a version of the invention in acontracted form mounted on a catheter coaxially arranged with asteerable dilatation catheter.

FIG. 9B is a plan view depicting the stent and catheter in an expandedform.

FIG. 9C is a plan view of the stent and dilatation catheter of FIG. 9Adepicting the stent, partially cut away to show the dilatation balloon,in an enlarged state whereby the ends of the stent are locked in anenlarged form.

FIG. 10 is a plan view of another embodiment of the locking devicedepicted in an unrolled state.

FIG. 11 is a plan view depicting one method of attaching the lockingring of FIG. 10 to the body of the stent.

FIG. 12A is a perspective view of another embodiment of the locking ringdepicted in a reduced diameter state.

FIG. 12B is a perspective view of the locking ring of FIG. 12A in anexpanded diameter form.

FIG. 13A is a plan view depicting an embodiment of the locking ring in areduced diameter form.

FIG. 13B is a perspective view depicting the embodiment of the lockingring of FIG. 13A in an expanded diameter form.

FIG. 14A is a perspective view of an embodiment of the stent and lockingrings depicting the stent in its original, reduced diameter form.

FIG. 14B is a perspective view of the stent of FIG. 14A in a fullyexpanded form with the ends locked in place depicted within the lumen ofa vessel.

FIG. 15A is an enlarged plan view depicting a portion of the locking endassembly of the stent of FIG. 14A.

FIG. 15B is a partial enlarged plan view of the locking end of the stentof FIG. 14B depicted in an enlarged diameter form.

FIG. 16 is a partial cross-sectional view taken along the line 15--15depicting an embodiment showing the attachment of the locking ring tothe interior of the stent body.

FIG. 17 is a partial cross-sectional view taken along the line 15--15depicting an alternative orientation and attachment of the locking ringto the exterior of the stent body.

FIG. 18A is an enlarged partial plan view depicting an alternativeembodiment where the locking end and the stent expandable body aremanufactured as a single piece in a reduced diameter form.

FIG. 18B is an enlarged partial plan view depicting the stent of FIG.18A in an enlarged diameter form.

FIG. 19A is a perspective view of an embodiment of the stent and lockingrings, depicted in a reduced diameter form, wherein the elements of theexpandable body are linearly shaped.

FIG. 19B is a perspective view depicting the stent and locking rings ofFIG. 19B in an enlarged diameter form.

FIG. 20A is a planned view depicting an embodiment of the invention in acontracted form mounted on a pair of inflatable balloons in tandemarrangement wherein the distal portion of the locking ring is mounted onthe distal balloon and the proximal locking ring is mounted on theproximal balloon.

FIG. 20B is a plan view depicting the stent and catheter wherein thestent body has been expanded.

FIG. 20C is a plan view of the stent and dilatation catheter of FIG. 20Adepicting the stent partially cut away to show the two dilatationballoons expanding the locking rings on the stent.

FIG. 20D is a cross-sectional view taken along line 20D--20D depictingthe coaxial arrangement of the outer member and the inner member each ofwhich carries one of the dilatation balloons.

DETAILED DESCRIPTION OF THE INVENTION

It is desirable to provide a stent for repairing vessel walls which hasthe capability of being flexible when expanded from a reduced to alarger diameter and which can be expanded and contracted in thepatient's vessel to ensure proper location and fit. It is also desirableto provide such an expanded stent with a locking mechanism that willlock the stent in its expanded state without sacrificing the flexibilityor radial strength of the stent. The present invention achieves theseadvantages.

Stent deployment can be accomplished by means of a two-stage processwhich allows the physician to abort the procedure if desired or if acomplication develops. In the first stage, the body of the stent isexpanded and then evaluated for such criteria as location relative tothe stenosis and size relative to the vessel in which it resides. Atthis stage expansion is reversible and the decision to implant the stentcan be aborted. The second stage expands and locks the ends of the stentin place so that the stent remains permanently implanted.

As shown by FIGS. 1-4, the invention is embodied in a stent 1 having anexpandable body 5 with locking rings 15 and 25 located at ends 10 and 20of the stent body.

The stent body is comprised of a plurality of helically shaped elements32 having ends 35 located at each end of the element. The stent 1 can beformed from a flat sheet of stainless steel or other suitable material,or it can be cut from a section of stainless steel hypotube. When formedfrom a flat sheet it is rolled to form a cylinder, and may have aplurality of helically shaped cuts 30. The helically shaped cuts extendfrom the center of the cylinder outward, cutting the cylinder intohelically shaped elements 32. The cuts can optionally be formed in sucha way that a very small connection is left between the ends 35 ofindividual helical elements 32, to hold the stent in a contracted,reduced diameter form. These connections are severed when ends 10, 20are expanded during implantation. The helically shaped elements 32 mayalso have openings, depicted as holes 31 in FIG. 2 and as slots 33 inFIG. 3, cut into them to reduce weight without sacrificing radialstrength or stiffness.

FIG. 1 depicts an embodiment of stent 1 in a contracted state having areduced diameter. In this state the outer diameter of the stent issubstantially the same over its entire length, including the two lockingends 10 and 20. This reduced diameter state allows the stent to beslidably engaged on the distal end of a suitable catheter, andintroduced into a patient's vasculature.

FIG. 2 depicts the stent in an intermediate state where the body 5 ofthe stent 1 has an enlarged diameter, but the locking ends 10, 20 of thestent remain in a contracted, reduced diameter. This intermediate stateis achieved, due to the construction of the helical elements 32 of theexpandable body 5, by either twisting the ends of stent 1 in a counterrotating manner relative to each other, or by twisting and at the sametime reducing the overall length of the stent by reducing thelongitudinal distance between ends 10 and 20. Further illustration ofthis process is presented below.

FIG. 4A is a perspective view of a locking end representative of lockingends 10, 20. The helically shaped elements 32 of the expandable body 5have ends 35 with slots 50 adapted to receive a locking ring 15. Thelocking ring has a plurality of teeth 52 either along both its first andsecond edges, or only along one edge. These teeth 52 are formed toengage the edges of slot 50 in such a way that the teeth 52 may slidethrough slot 50 in only one direction. This allows the locking end toexpand to a second enlarged diameter state, but prevents contraction toa reduced diameter state.

FIG. 3 depicts the stent 1 in a final enlarged state. In this view, boththe expandable body 5 and the locking ends 10, 20 have expanded largerdiameters suitable for fixing the stent in position within a vessel.FIG. 4B is a perspective view of locking end 10 illustrating how theends 35 of the helical elements 32 of the expandable body 5 move apartas the end 10 expands, and how teeth 52 on locking ring 15 engage theedges of slot 50 to lock the end 10 in an enlarged diameter. FIG. 5C, across-sectional view taken along the line 6--6 of FIG. 3, furtherillustrates the interaction between helical element ends 35, lockingring 15 and locking ring end 40.

FIGS. 5A-C and 6A-B depict the structure of the locking end in moredetail. Locking ring 15 has a first end portion 40 having a slot or aloop 41. The second end 45 of locking ring 15 is threaded through theends 35 of the helically shaped elements 32 of the expandable body 5 andthen through the slot 41 in locking ring end 40. Locking ring 15 issuitably long so that it is retained within the slot 41 of locking ringend 40 when the stent end 10 is fully enlarged during implantation, asshown in FIG. 5C. The teeth 52 on the edges of locking ring 15 allow theslots 50 in the ends 35 of the helical elements 32 to slide along thelocking ring as the stent end 10 of stent 1 expands, but do not allowthem to return to their original position, thus locking the ends 10, 20of the stent in an enlarged diameter state.

FIGS. 5B-C depict locking ring 15 with locking ring end 45 threadedtowards the interior of the stent. Locking ring 15 may also be threadedthrough expandable element ends 35 in the alternate manner depicted inFIG. 6A, with locking ring end 45 overlapping the exterior of the stent.Either alternative is equally suitable in the present invention.

Several locking mechanisms can be employed to securely fix the lockingends in an expanded and locked configuration. As shown in FIGS. 7A and7C, locking ring 15 extends through a pair of slots 50 which are formedin ends 35. The bridge 55 is slightly raised or curced to allow lockingring 15 to pass through slots 50. Teeth 52 engage the slots 50 as thelocking ring 15 is expanded. As can be seen in FIG. 7A, teeth 52 pointin one direction so that after locking ring 15 is expanded the teethengage the slots 50 and prevent locking ring 15 from collapsing orrecoiling. Another embodiment for locking ring 15 in its expandedconfiguration is shown in FIGS. 7B and 7D. The method of locking is thesame as that described for FIGS. 7A and 7C.

FIG. 8 is another embodiment of the present invention. Stent 1 can beformed from a plurality of helically shaped members 60, each having atleast one end having a toothed tab 65 projecting perpendicular to thelongitudinal axis of member 60, and a slot 70.

In a first, contracted state, helically shaped members 60 are arrangedto form a substantially cylindrical stent. In this arrangement, toothedtabs 65 are threaded through slot 70, in such a fashion that adjacenttabs 65 overlap each other. The tabs remain overlapping in a contractedstate during expansion of the body of the stent. When the stent has beenpositioned within a vessel lumen, the ends of the stent are thenexpanded by any suitable means, such as inflating an inflatable balloonon the distal end of a dilating catheter, such as shown in FIG. 9C,causing a reduced overlap of tab 65 at each end of each member 60 of thestent. As inflatable balloon 210 continues to expand, the toothedportions of tab 65 interact with slot 70 to engage in a locking manner,and, once engaged, to stay engaged with a high degree of reliability.

An alternative embodiment of the locking ring is depicted in FIG. 10.Locking member 300 is substantially shorter than the embodiment of thelocking ring shown in FIG. 5A. Locking member 300 is designed to spanthe distance between two adjacent helically shaped element ends 35. Asdepicted in FIG. 11, a plurality of locking members 300 are used toconnect helically shaped elements ends 35 to construct the stent inrolled form. FIG. 11 illustrates how locking member 300 is used tointerconnect ends 35 of the helically shaped elements 32 to form thestent. A plurality of helically shaped members 32 are arranged so thatlocking member 300 can be slid through the slots 50 in the ends 35 oftwo adjacent helically shaped members 32. As shown in FIG. 11A, lockingmember ends 310 and 320 overlap other locking members 300 when the stentis in a reduced diameter form. When the locking end is expanded, asdepicted in FIG. 11B, the overlap of individual locking members 300 issubstantially reduced. Each locking member has teeth 352 situated on atleast one of its longitudinal edges that are designed to engage theedges of slot 50, thus irreversibly locking the ends of the stent in anenlarged diameter form. It will be obvious to one skilled in the artthat other embodiments of a locking device can be incorporated into anintravascular stent that will allow the stent to be used during thetwo-stage implantation process described herein. Any combination oflocking device and reversibly expandable stent body construction thatallows the body of the stent to be first expanded and then, in a secondstep, irreversibly locked into place will be within the scope of thisinvention.

Examples of other potential embodiments of the present invention aredescribed in FIGS. 12-14. The previous embodiments have shown thelocking device as an expandable device that expands byway of the lockingring end or member moving in relation to the ends 35 of the stent. It ispossible, however, to construct the locking device from a material thatundergoes irreversible plastic deformation when it expands. Such anembodiment of the locking device is disclosed in FIGS. 12A and 12B. InFIG. 12A, locking ring 400 is depicted in a contracted, reduced diameterform. Locking ring 400 is depicted having teeth 452 as discussedpreviously to engage slots 50 located on ends 35 of helical elements 32.Locking ring 400 also has openings 420, which can be any shape, forexample round holes, slots, or ovals. The addition of holes 420 andtheir location on the locking device 400 allows the device toirreversibly plastically deform when a force greater than the elasticlimit of the material is applied to expand the locking device. FIG. 12Billustrates the locking ring 400 of FIG. 12A in an expanded largerdiameter form. Locking device 400 is shown having cut outs 425 on bothedges that allow the width of the locking device to reduce as it isenlarged.

FIG. 13A shows a locking ring 500 similar to that shown in FIG. 12Aexcept that the openings are depicted as slots 520 and there are noteeth on the edges. FIG. 13B depicts the stent of FIG. 13A in expandeddiameter form.

Although previous embodiments have shown locking devices such as thatdepicted in FIG. 5A as threading through slots on the ends of thehelically shaped members 32, it is possible to construct a stent such asthat shown in FIG. 14A by attaching the locking rings to the ends of thestent. Stent 600 is shown in a rolled reduced diameter form havinghelically shaped elements 632 comprising an expandable body 605. Thehelically shaped elements 632 are separated by slots or slits 630.Attached to each end are locking devices 610 and 620. FIG. 14B depictsthe stent of FIG. 14A in its expanded enlarged diameter form within thelumen of a vessel 680 compressing a flap 685 against the vessel wall.

Locking devices 610 and 600 can be attached to the ends of stent body605 in a variety of ways. FIGS. 15A and 15B depict one embodiment ofsuch an attachment method. In this embodiment, individual helicalelements 632 having tabs 635 on each end are attached to locking device610 using a suitable adhesive, bio-compatible solder, spot welding, orother suitable attachment means. FIG. 15B depicts the device of FIG. 15Ain an expanded enlarged diameter form. Tabs 635 can be attached tolocking device 610 on either the internal surface as depicted in FIG.16, or on the external surface of locking ring 610 as depicted in FIG.17. Either attachment means is suitable since expansion of the lockingdevice 610 is independent of the placement or method of attachment ofthe tabs 635.

FIGS. 18A and 18B illustrate another embodiment of the invention whereinthe locking devices and the helically shaped elements 732 are fabricatedfrom a single piece or sheet of an appropriate material that is capableof irreversible plastic deformation. The stent 700 can be fabricatedfrom a single sheet with an appropriate metal, using a computercontrolled laser or waterjet cutter. The laser of waterjet cutter isused to cut openings 720, notches 750 and slots 730. Once the complexshape of the locking device 710 and the expandable body 705 has been cutfrom the sheet of material, the sheet is rolled into a cylindrical formand the longitudinal edges of the sheet are joined using a suitableattachment method. The attachment method can be adhesive, solder, spotwelding, brazing, or any other metal joining method suitable for joiningthe edges of an intravascular stent. Construction of a stent in thismanner is particularly beneficial in that it allows high quality,reliable, and low cost manufacturing of the stent.

FIGS. 19A and 19B illustrate another embodiment of the invention whereinthe individual elements 730 that comprise the expandable body 705 ofstent 700 are linear in shape and are separated from each other by slotsor cuts 740. Expansion of expandable body 705, as depicted in FIG. 19B,causes the linearly shaped elements 730 to bow radially outwardly andcontact the vessel wall. Expansion of locking ends 710, 720 is similarto other embodiments of the invention previously described.

In another embodiment of the invention as depicted at FIGS. 20A-D, stent1, in its contracted reduced diameter state, is mounted on the distalend of catheter 800 with locking ends 10, 20 slidably engaging proximalballoon 840 and distal balloon 845 respectively. A steerable dilatationcatheter 800 having a pair of tubular members coaxially arranged isprovided in order to implant stent 1. Dilatation catheter 800 has anouter member 810 and an inner member 815 which are co-axially arrangedand can be moved axially with respect to one another. Dilatation balloon840 is mounted on outer member 810 and distal balloon 845 is mounted oninner member 815. The outer member is attached at its proximal end toknob 811 which can be rotated and in turn rotates outer member 810 andproximal balloon 840. Likewise, inner member 815 is attached at itsproximal end to knob 816 and when the knob is rotated it impartsrotational movement to inner member 815 and distal balloon 845. Further,knob 816 can be moved axially with respect to knob 811 thereby creatingaxial displacement between the balloons.

Referring more specifically to FIG. 20B, knobs 811 and 816 have beencounterrotated and knob 816 withdrawn proximally so as to impartrotational movement to stent 1 and to simultaneously shorten thedistance between locking ends 10, 20. Thus the body of stent 1 isexpanded while locking ends 10, 20 remain in engagement with proximalballoon 840 and distal balloon 845 respectively. As can be seen in FIG.9C, proximal balloon 840 and distal balloon 845 have been inflated,thereby expanding locking ends 10 and 20 to their fully expanded andlocked positions. Thereafter, the balloons are deflated and the catheterassembly is withdrawn from the vasculature or body lumen 850 leaving theexpanded stent implanted at the body lumen 850. FIG. 20D depicts thecoaxial arrangement of outer member 810 and inner member 815 withguidewire 220 passing through the inner member.

Referring to FIGS. 9A-C for example purposes, the operation of the stentof the present invention will be described. As shown in FIG. 9A, thestent 1, in its contracted reduced diameter state, is mounted on thedistal end of a catheter 100 with locking ends 10, 20 slidably engagingcollars 140, 145 respectively. A steerable dilatation catheter 200having a dilatation balloon 210 mounted on a tubular member 180,co-axially arranged on a core member 220, and terminating with a helicalcoil 230 is percutaneously introduced into a vessel and tracked byfluoroscope until the location of the vascular lesion to be treated isreached. The catheter 100 is then mounted on the steerable dilatationcatheter 200 by threading tubular member 180 through the central lumen125 of the catheter 100. The catheter 100 is then slidably moved alongtubular member 180, its progress tracked by fluoroscope, until the stent1 is positioned at the site to be repaired.

To facilitate visualization of stent 1 at the repair site, one or bothof the locking rings 15 at the ends 10, 20 may be radiopaque. Theradiopaque material can be gold, platinum-iridium, or any other commonlyknown material visible under fluoroscopy. It should be apparent thatrendering only the rings 15, located at the ends 10, 20 of the stent 1,is advantageous because the rings can be used as markers to define thearea where the stent will contact the vessel wall without obscuring therepair site. This allows the physician to ensure proper positioning ofthe stent.

Collar 140, depicted here separated from catheter body 110 for clarity,is, in actuality attached to catheter body 110. Collar 145 is mounted onan inner tubular member 120, co-axially arranged within catheter body110 and having a central lumen 125. Both inner tubular member 120 andcentral lumen 125 extend to the proximal end of catheter body 110.

Using an embodiment shown in FIG. 9A as an example, when the stent 1 isproperly positioned, the physician rotates and pulls knob 122 mounted onthe proximal end of inner tubular member 120 in a proximal direction.Collar 140 remains essentially stationary while collar 145 is pulledaxially in a proximal direction by inner tubular member 120. As theaxial distance between collar 140 and 145 decreases, force is applied tolocking ends 10, 20 and acts to radially expand and reduce the length ofstent 1. Due to the shape of the helical elements 32 of expandable body5, the forces expand the stent body 5 radially outwardly into contactwith the vessel wall, and reduces its length. This expansion causes thecentral portion of expandable body 5 to expand radially outwardly andcontact the vessel walls, but leaves locking ends 10, 20 still engagedon collars 140, 145 in a contracted, reduced diameter state. With astent as shown in FIGS. 19A and 19B, which has non-helical slits, thereis no need to counterrotate the locking ends as the body of the stent isexpanded by axial movement. This is not the case when the stent ishelically shaped.

When stent 1 is formed of helically shaped elements 32, reducing theaxial length of stent 1 while simultaneously rotating the locking 10,20, either individually or together, results in the stent expandingradially outwardly into contact with the vessel wall. Collars 140, 145may be attached to the catheter body 110 or inner tubular member 120respectively in such a manner that the collar turns freely as the axiallength of the stent 1 is shortened. Preferably, the collars are firmlyattached to their respective catheter members. This allows the physicianto rotate knob 122 as he pulls knob 122 in a proximal direction, thusassisting the expansion of stent 1.

As will be apparent from FIGS. 19A-B, rotation of locking ends 710, 720does not occur when stent 700 is formed of linearly shaped elements 730.

While knob 122 is depicted in FIG. 9A as the means for rotating innertubular member 120, it will be apparent that any means capable ofgrasping the inner tubular member 120 or catheter body 110 and applyingtorque to the catheter body 110 or inner tubular member 120 can be used.

Alternatively, catheter 100 may be constructed so that inner tubularmember 120 is rotated causing collar 145 to rotate while collar 140remains fixed. When the inner tubular member is rotated in anappropriate direction, the rotation causes the expandable body 5 toexpand, but leaves locking ends 10, 20 in a first reduced diameterstate.

A principle advantage of the present invention is that once the stentexpandable body 5 has been expanded, the physician can check thepositioning and sizing of the stent 1 in relation to the vascular defectto be repaired. If stent size or positioning is not adequate to repairthe defect, the stent may be contracted to a reduced diameter and eitherwithdrawn from the vessel, or repositioned before final expansion andimplantation. All other implantable prior art stents undergoirreversible expansion during implantation. Thus, the present inventionis a major step forward in the repair of vascular defects.

Contraction of expandable body 5 of stent 1 to a reduced diameter stateis accomplished in essentially the reverse order of expansion. Bypushing inner tubular member 120 in a distal direction andsimultaneously rotating one or both locking ends 10, 20, collar 145 willmove in a distal direction relative to collar 140. This causes lockingend 20, slidably engaged on collar 145, to move in a distal direction.Since locking end 10 is engaged to collar 140 which is attached to thecatheter body 110, the distal motion of collar 145 and rotation oflocking end 20 results in an increase of the axial length of stent 1,thus causing the expandable body 5 to contract radially inwardly andreturn to a contracted, reduced diameter state. Once this reduceddiameter state is attained, the stent 1 and catheter 100 may be eitherwithdrawn from the vessel or repositioned.

When the physician is satisfied with the sizing and placement of stent 1in the vessel, final implantation is accomplished as follows. Catheter100 is slowly withdrawn in a proximal direction, releasing locking ends10, 20 of stent 1 from collars 140, 145 respectively. It should be notedthat while locking ends 10, 20 engage collars 140, 145 with sufficientforce to remain engaged during the expansion of expandable body 5 to anenlarged diameter, contact with the vessel wall is sufficient to retainthe stent in position and overcome the engaging force when catheter 100is slowly withdrawn.

When catheter 100 has been withdrawn leaving stent 1 in position, thesteerable dilatation catheter 200 is moved proximally until theexpandable portion of the dilatation balloon 210 is positioned withinthe length of stent 1. The dilatation balloon is then expanded byforcing a noncompressible fluid through tubular member 180. Theexpansion of balloon 210 causes locking ends 10, 20 to expand to anenlarged diameter state, as shown in FIG. 9C. The teeth 52 of lockingring 15 irreversibly engage the edges of slots 50 of edges 35 and slot40 of locking ring 15 to lock the stent 1 in an enlarged diameter state,thereby holding the vessel open. The dilatation balloon is thendeflated, and the steerable dilation catheter is withdrawn from thevessel leaving stent 1 implanted.

Any embodiment of the stent may be formed from a variety of materials,including bio-compatible and bio-resorbable polymers, thermal shapememory polymers or metals, bio-compatible metals, stainless steel, orsuper elastic materials, such as nickel-titanium alloys. A materialconstituting the stent can be a thin flexible polymer material, such asa polyimide, coated with a thin strengthening material comprising apyrolytic carbon. Furthermore, in all of the embodiments of stentsdisclosed herein, the material comprising the stent may be made of abio-degradable material, and may be a material impregnated with a drug,so the stent may locally treat a particular lesion or disease.

Expansion of stent 1 from a reduced diameter form into an expandeddiameter form may be performed by any means that can expand the centralbody of the stent either by twisting the ends while simultaneouslyshortening the longitudinal length of the stent, and then subsequentlyexpanding the ends of the stent and locking rings into a final enlargeddiameter form. Furthermore, the present stent is not limited to use incoronary arteries and over-the-wire angioplasty catheter systems; thestent may also be deployed in any body lumen by any suitable means suchas use of a so-called rapid exchange catheter system.

The stent of the present invention as described in all of the foregoingembodiments may be used not only in cardiovascular procedures, but alsoin urinary, prostate, renal, cerebral, nasal, auditory, rectal, aorticand other medical procedures.

Furthermore, it should be understood that any dimensions associated withthe above described embodiments are not intended to limit the inventionto only those dimensions. For example, while certain dimensions might beappropriate for a stent used in a coronary artery, these same dimensionsmight not be suitable for a stent used in other areas of a patient'svasculature or other body lumen. It is also understood that the drawingsare not necessarily to scale.

Other modifications can be made to the present invention by thoseskilled in the art without departing from the scope thereof. Whileseveral particular forms of the invention have been illustrated anddescribed, it will also be apparent that various modifications can bemade without departing from the spirit and scope of the invention.

I claim:
 1. An intraluminal stent implantable in a body lumen,comprising:a cylindrical body formed from at least one strip disposedalong a longitudinal direction, having a first end and a second endperpendicular to the longitudinal edges of said strip, further having atab and a slot for receiving a tab located at the first end and thesecond end, said body and said ends further having a first reduceddiameter and an adjustable second expanded diameter, wherein at leastone said end of said at least one strip is radiopaque.
 2. Anintraluminal stent implantable in a body lumen, comprisinga cylindricalstent body having a first reduced diameter and an adjustable, secondexpanded diameter; a first end and a second end on said cylindricalstent body; at least one ring capable of expanding from a first reduceddiameter form to a second, expanded diameter form; attaching means forattaching said ring to one of said ends of said cylindrical stent body;whereby said ring undergoes irreversible plastic deformation when it isexpanded from said first reduced diameter form to said second expandeddiameter form, locking said cylindrical stent body in a second expandeddiameter.
 3. An intraluminal stent implantable in a body lumen,comprising:a body portion formed from a sheet, said sheet having a firstlongitudinal edge and a second longitudinal edge, further having a firstend and a second end wherein said body portion is formed into asubstantially cylindrical shape by joining said first longitudinal edgeto said second longitudinal edge; a plurality of helical cuts in saidsheet; a plurality of openings in said first end and said second end;means for expanding said first end and said second end from a firstreduced diameter to a second expanded diameter, so that said first endand said second end are expanded from a first reduced diameter to asecond expanded diameter, said first end and said second end undergoingirreversible plastic deformation and locking said stent in said secondenlarged diameter form.
 4. The intraluminal stent of claim 3, whereinsaid first end and said second end are radiopaque.
 5. A method forrepairing a patient's vasculature or other body lumen having an occludedor partially occluded portion, comprising:mounting an intravascularstent body on a catheter having means for expanding and contracting saidstent body, said stent body as mounted on said catheter having a firstreduced diameter; advancing said catheter to position said stent bodyacross the site of repair; expanding said stent body at said site ofrepair to engage said patient's vasculature; expanding a first end and asecond on said stent body for locking said first end and said second endin an adjustable, second expanded diameter; and withdrawing saidcatheter from said vasculature or other body lumen.